i always ask em "if the KJB isn't the preserved word of God, then what is? and please be specific in every way" i add that in in case they try saying the original languages, i always ask for a specific list of each individual text, because there is not one manuscript in the original language in the NT that is complete, i usually drive em nuts till they admit they don't know then i say something like "well brother/sister, i do know, and i want you to know to, that the KJV is the perfectly preserved word of the Lord"